Compactor machines are used extensively in construction projects to compact soil, asphalt, gravel, and other similar materials. Typically such machines include mechanisms that vibrate at controlled frequencies and amplitudes while pressing down on the surface of the material to be compacted. Such a machine and control is a machine control are disclosed in U.S. Pat. No. 7,089,823, issued Aug. 15, 2006, to Potts, the disclosure of which is incorporated herein by reference. Potts shows a vibratory compactor that uses vibrating mechanisms within compaction rollers. Vibrations are imparted to the rollers as the compactor machine is driven over the surface enhancing the compaction process. Each vibrating mechanism typically includes weights that rotate about a common axis, with the weights being eccentrically position with respect to the common axis to produce varying degrees of imbalance during rotation. The amplitude of the vibrations produced by the arrangement is varied by changing the relative position of the eccentric weights to vary the average distribution of mass. Varying the rotational speed of the weights about their common axis changes the frequency of the vibrations produced by the arrangement.
It is known to determine the degree of compaction of the material by monitoring the reflected vibrations that are returned to the compactor machine. Those reflected vibrations may be sensed by appropriate sensors carried on the machine. The vibrations may in fact pass from the compaction surface, through the rollers, and be detected by appropriately positioned sensors on or adjacent the roller support. As is known, optimal compaction varies from material to material, and it is preferable that the material not be compacted too much or too little. To achieve this, the degree of compaction can be determined by sensors on the machine which receive reflections of kinetic energy. The sensors are mounted at a distance from the machine control, and the sensor outputs must therefore be supplied to the machine control, typically by cable. Additionally, the sensors typically require a power supply, and this power also is provided over additional wires or cables. Such wires or cables can be problematic, however, for a number of reasons. For example, they run to various parts of the machine which can be subject to a harsh environment, causing them be damaged or broken fairly quickly. Further, sensor wires and cables can limit the relative movement of machine components.